/*
    Copyright 2009 Spencer B. Koehler, Ph.D.

    This file is part of the Brillig Toolkit.

    The Brillig Toolkit is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    The Brillig Toolkit is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with The Brillig Toolkit.  If not, see <http://www.gnu.org/licenses/>.
*/
package org.brillig.util.logic;


/**
 * Interface for a function to verify "truth" of input.
 * <p>
 * @author Spence Koehler
 */
public abstract class TruthFunction <T> extends LogicalStatement <T> {
  
  /**
   * Evaluate the "truth" of the input.
   * <p>
   * NOTE: A null logical result is interpreted as not-applicable and is "ignored".
   *       Concrete "true" and "false" responses are required for "not" logic.
   */
  public abstract LogicalResult<T> evaluateInput(T input);

  /**
   * Safely downcast this LogicalStatement as a TruthFunction.
   */
  public final TruthFunction<T> asTruthFunction() {
    return this;
  }
}
